A wide variety of downhole tools, such as service tools, for example, may be used within a well bore in connection with producing hydrocarbons or reworking a well that extends into a hydrocarbon formation. Downhole tools such as frac plugs, bridge plugs, and packers, for example, may be used to seal a component against casing along the well bore wall or to isolate one pressure zone of the formation from another. Such downhole tools are well known in the art.
Before the production or reworking operation, these downhole tools must be run in and set within the well bore, and after the production or reworking operation is complete, these downhole tools must be removed from the well bore. Tool removal has conventionally been accomplished either by milling or drilling the tool out of the well bore mechanically, or by complex retrieval operations using traditional run-in and retrieval devices.
One type of traditional run-in and retrieval device requires normal right-hand rotation to form a connection between a threaded mandrel and a threaded sleeve, and reverse rotation to disconnect the threaded mandrel from the threaded sleeve. Such reverse rotation is undesirable because it may cause another threaded connection in the tool string to disconnect, or another tool in the tool string to break, before the threaded mandrel and the threaded sleeve disconnect.
Therefore, the next generation of run-in and retrieval device comprises a threaded mandrel that inserts longitudinally into a threaded, ratcheting C-ring to form a releasable connection therebetween. The full weight of the tool string below the device is supported by the interaction between the mandrel and the C-ring ratchet teeth. The C-ring only allows longitudinal movement of the mandrel in one direction so that longitudinal removal of the mandrel is prevented. In this design, a left-hand thread is used so that disconnection of the device is accomplished by normal right-hand rotation, thereby preventing undesired disengagement or breakage of other tool string joints.
Under certain conditions, such as when servicing an offshore extended reach well from a floating platform, there are several disadvantages to using a C-ring type run-in and retrieval device. First, a plurality of full rotations, such as ten (10), for example, must be applied to disengage the mandrel from the C-ring, and a longitudinal force on the mandrel will re-engage the ratchet teeth. Thus, when rotating the mandrel to disengage it while operating from an offshore floating platform that moves up and down in response to wave forces, a longitudinal force may inadvertently be applied to the mandrel, thereby re-engaging the ratchet teeth as the platform heaves. Depending upon wave conditions, this process could be repeated several times before successfully disconnecting the mandrel from the downhole tool. In addition, the C-ring type device is not capable of supporting a significant weight, such as 500 tons, for example, as would be required for a run-in and retrieval device used to support long tool strings for extended reach wells.
Therefore, a need exists for a run-in and retrieval device that easily connects and disconnects from a downhole tool when operating from an offshore floating platform. Further, a need exists for a run-in and retrieval device capable of supporting a significant quantity of weight of the tool string below the device.